Current communication networks have increasingly higher requirements for the transmission bandwidth, and accordingly, the technology of synthesizing optical signals of multiple wavelengths into one signal (wavelength division multiplexing, WDM) for transmission in an optical fiber emerges. In a WDM system, especially a dense WDM (DWDM) system (e.g., a WDM system having wavelength intervals less than or equal to 50 GHz), the wavelength of each wavelength division multiplexed optical signal is required to have high precision and stability. Since the wavelength of an optical signal output from a laser varies with a die temperature of the laser, a system is required to lock and control the die temperature of each laser.
In the prior art, a single control system locks and controls die temperatures of multiple lasers. FIG. 1 shows a system for controlling wavelength of each optical signal output from a multi-path laser. Optical signals are generated by optical transmitters and are synthesized into one signal by a multiplexer. Relevant wavelength information is obtained after a series of signal processing operations are performed on the signal. A controller obtains a control amount of a die temperature of each laser (i.e., optical transmitter) by calculation and delivers it to the corresponding laser. This system controls die temperatures of the independent lasers in turn by a polling method, so as to finally realize the control and locking wavelength of optical signal output from the laser.
In the above multi-path WDM system, an integrated laser array is generally used to output the synthesized multiple optical signals. Such an array arrangement of the lasers increases cross-talk coupling between the die temperatures of the lasers, that is, the adjustment of the wavelength of optical signal output from a certain laser will bring unexpected changes to wavelengths of optical signals output from other lasers. However, the above system for controlling wavelengths of optical signals output from the multi-path laser does not take such cross-talk coupling into consideration, and thus cannot perform decoupling control on the thermal cross-talk between the lasers, so that the convergence time for wavelength control is lengthened.